Oathkeeper

Jaime Lannister's Valyrian sword which he gifts to Brienne. It was orignally House Starks'Greatsword Ice. In the books after Lord Eddards' death, Tywin Lannister had it melted down, and had master blacksmith Tobho Mott forge it into two blades, Widow's Wail and Oathkeeper. Oathkeeper has the ripple of a Valyrian blade but is black and Lannister crimson. In the show it resembles normal steel and has no remarkable coloring.